Can Bad Ignition Switch Cause Rough Idle

Having a bad ignition switch is something you cannot even wish for your enemy. It can cause several problems to the car but can it cause rough idle?

A bad ignition switch can cause a rough idle. Since the role of an ignition switch is to keep the engine on and at the same time turn It off, if affected will definitely lead to a diverse problem that exceeds causing a rough idle alone, it can also cause a complete engine failure.

What Is A Rough Idle?

Rough idling is a common error that comes with owning a car. You can simply tell when a car is rough idle because it’s obvious.

To identify if the problem is a rough idling, you will experience a shaking and bouncing sensation. Aside from that, there are also odd sounds that you might possibly hear if you pay close attention.

A rough idling car also expresses’ inconsistent RPM counts. A car in its normal condition should have an RPM of about 1000. If at all your vehicle has figures way lesser than this or higher than this, you probably have idling issues.

There are a few common reasons why your car can be idling rough, a few of them include:

A Vacuum Leak

In every car, there are hoses, numerous hoses holding on to different functions in which they create a vacuum for air and fuel likewise.

When these hoses wear out and begin to leak, it allows unusual entry of air which then mixes up with the fuel.

At the very end, it causes your engine to misfire. When your engine misfires, it then results in a rough idle with a high RPM value (A high RPM value is always above 1000).

Spark Plugs

Spark plugs also tend to cause rough idling.  A spark plug assists with the ignition of the air/fuel mixture within the combustion engine but it uses the electrical power received from the ignition coils to initiate the ignition.

When there is an error in the installation of the spark plug or it has gone bad, it can cause the fuel to burn at an inconsistent rate. If this proceeds further without any attention, it could result in rough idling while driving.

Can Bad Ignition Switch Cause Rough Idle?

Yes, a bad ignition switch can cause you a rough idle. Since the sole purpose of an ignition switch is to keep a car switched on and turned off, if it goes wrong, can also make other parts of the car go wrong.

A bad ignition switch might not directly cause your car to rough idle but it has its hand-stained as well with the crime.

These are the following things a bad ignition switch has a direct effect on which then results in a rough idle.

1. Your Battery Can Be Affected First

If you want to be a little more civilized when you notice your car rough idling, the first thing that should pop into your mind is to check your battery first.

Since a bad ignition switch is an electrical problem, and a battery is also one of the devices that powers the electrical components of the car, then we could trace a misfortune to it in this case.

A bad ignition switch can cause your battery to go wrong, be damaged, or be prematurely fried. If this happens, it automatically causes your engine to misfire which then causes your car to rough idle.

But, if you notice that your battery is as healthy as the horse, then you could check other things an ignition switch may also affect.

2. A Faulty Oxygen Sensor

Another factor you might want to consider is the oxygen sensors of your car. The oxygen sensor carries the burden of measuring the amount of oxygen in your car exhaust.

With the data your oxygen sensor can chunk together, the engine makes quality decisions with it. One of the decisions the engine makes is to regulate the timing of your car’s spark plug.

A bad ignition has a direct effect on your oxygen sensors and affects the readings the oxygen sensor might produce. When your oxygen sensors begin to produce wrong readings, it can cause your car to rough idle.

A few other things can also cause your vehicle to rough idle like a faulty fuel injector or a problem with the combustion chamber but whichever one it is, you need a move on what to do when your car suddenly begins to rough idle.

What Can You Do If Your Car Is Rough Idling?

Now let’s assume the problem with your car rough idling is because of a bad ignition switch. There are a few pointers to things you could do to have it fixed, here are a few to consider.

Get A New Switch

Sounds simple, right? A faulty bad ignition switch needs a replacement so just have it replaced to fix the problem.

It’s something you can fix yourself after purchasing a new one. A new ignition switch ranges from $15-$100, and having someone fix it for you may also cause a few more.

Have The Contact Points Cleaned

The metal contacts inside the ignition switch also get corroded with exposure and with time cause a bad connection.

If you notice the metal contacts of the ignition switch are dirty or corroded, you can clean it up with these short processes.

  • Open the vehicle’s dashboard
  • Find the switch and open it with a screwdriver
  • Have the contact points cleaned with sanding paper
  • Add a small amount of Graphite lubricant to the cleaned contact surface. Be minimal with the padding.

After cleaning and lubricating, you could also have a further look at the contact springs – they are small pieces of metal with one of the ends bent over.

They could be broken and that could even be the problem. So when you have taken the courage to clean, you could as well have this checked and fixed if possible.

You Could Also Try Getting A New Battery

Don’t forget one of the first signaling parts of your car to a rough idling can be traced to a faulty battery. Have your battery tested for errors and if found, have it fixed or changed. It should solve the problem then.

But if after your efforts, you still notice some rough idling still going on while you drive; I suggest you take a trip straight down to a technician to professionally have things checked for you.

Other Problems an Ignition Switch Can Cause

The problems a damaged ignition switch can cause are easily relatable because the problems are crystal clear. Check them out.

1. It Stops The Engine From Starting Up

When there is a bad ignition switch, you should probably know that starting up your car will be a little strenuous because there won’t be a supply of power to the starter motor and other ignition-relating parts of the car that need the ignition switch to at its best performance.

If your engine isn’t starting up, you could relate it to a bad ignition switch but be sure not to be one-sided as there are other factors as to why your engine might not pick up. It could be that it has a bad battery that needs a supporting hand (Jumpstarting) before it can come up.

2. A Malfunctioning Of Electrical Accessories

A bad ignition switch can cause the interior lights and other lights like that of the dashboard to turn on and off momentarily.

This is bad for the vehicle as it will cause more damage due to power imbalance. No one likes to see the check engine warning light on his dashboard.

3. You Could Also Experience Difficulty Turning The Keys

You probably have experienced this one or two times, only if you have been driving for a long time, not the new folks who just got behind the wheel.

A stuck key is another reason why you should blame it on your ignition switch. It can cause your engine not to start at all or if it does start, it stays running even after a hard time turning the car off.

Other Things That Can Cause a Rough Idling

As mentioned earlier, a leaking vacuum and a damaged spark plug can cause your car to experience rough idling but there are also a few more you might want to consider.

A Dirty Fuel Injector

A mixture of dirt with your fuel can cause your engine to experience a decrease in fuel mileage which automatically isn’t a good strategy for a better fuel efficiency experience.

You surely will have some problems when your fuel injector is dirty or broken and one of the problems is rough idling.

Air Filter

Dirt in your air filter is also a problem you don’t want coming up at all times as it can be frustrating, yet resource-consuming.

When dirt accumulates in your air filter, it prevents a complete combustion cycle which results in a misfire that proceeds to cause your engine to experience rough idling.


There are many reasons why your vehicle can experience rough idling, you should consider a closer look at the above-mentioned but if you can’t possibly see what is wrong, why not have yourself visit a technician?